The present invention relates to pods for transporting semiconductor wafers in a semiconductor production facility. More particularly, the invention relates to an apparatus and method for removing particles from semiconductor wafer pods to prevent particle contamination of wafers in a semiconductor production facility.
A standardized mechanical interface (SMIF) system is disclosed in U.S. Pat. Nos. 4,532,970 and 4,534,389. Such a SMIF system is designed to reduce particle fluxes onto semiconductor wafers and/or reticles in a semiconductor production facility. The SMIF system prevents or minimizes particle contamination of the wafers during transport and storage of the wafers by ensuring that gaseous media surrounding the wafers is essentially stationary relative to the wafers, and further, by preventing exposure of the wafers to particles from the ambient environment.
The SMIF concept is based on the use of a small volume of motion- and contamination-controlled, particle-free gas to provide a clean environment for semiconductor wafers and other articles. Further details of one such system are described in a paper entitled, xe2x80x9cSMIF: A TECHNOLOGY FOR WAFER CASSETTE TRANSFER IN VLSI MANUFACTURINGxe2x80x9d, by Mihir Parikh and Ulrich Kaempf, Solid State Technology, July 1984, pp. 111-115.
SMIF systems are designed to prevent contamination by particles which range from below 0.02 xcexcm to above 200 xcexcm. Due to the small geometries of the components in modern semiconductor integrated circuits, particles falling within this size range can significantly adversely affect semiconductor processing. Current geometry sizes for semiconductor integrated circuits have reached less than half a micron, and those circuits are adversely affected by particles having a size as small as 0.01 xcexcm. In the future, semiconductor integrated circuits will be marked by increasingly smaller geometry sizes, requiring protection from contamination by correspondingly smaller particles.
A SMIF system has three main components: (1) sealed pods, or containers, each of which has a minimal volume and is used for storing and transporting cassettes holding reticles or wafers; (2) enclosures placed over cassette ports and wafer processing areas of processing equipment such that the environments inside the pods and enclosures (after being filled with clean, dry air) become miniature clean spaces; and (3) a transfer mechanism which is used to load and unload wafer cassettes from a sealed pod without contamination of the wafers in the wafer cassette from external environment.
Semiconductor wafers are stored and transported in pods, and are transferred from a pod to processing equipment in the following manner. First, a pod is placed at the interface port of a processing tool. Each pod includes a box and a box door designed to mate with doors on the interface ports of the processing equipment enclosures. Then, latches release the box door, and the box door and the interface port door are opened simultaneously such that particles which may have adhered to the external door surfaces are trapped or sandwiches between the box and interface port doors. A mechanical elevator lowers or translates the two doors, with the cassette riding on top, into the enclosure-covered space. The cassette is transferred by gravity or a manipulator and placed onto the cassette platform of the equipment. After processing, the reverse operation takes place.
The SMIF system has proven effective for preventing or reducing particle contamination both inside and. outside a clean room, and provides at least a ten-fold improvement over the conventional handling of open cassettes inside the clean room. Thus, the SMIF system has significantly enhanced the functional integrity of semiconductor integrated circuits and increased the efficiency of semiconductor fabrication facilities.
One of the limitations of the SMIF system is that particle contamination remains a potential problem upon attachment of the pod to the processing equipment, as particles sandwiched between the box door of the pod and the interface port door of the processing equipment may become dislodged from between those elements and fall onto the semiconductor wafers as the wafers are lowered into the processing equipment. Conventional techniques for ameliorating these effects include manually wiping the bottom surface of the pod box door to clean the door of the particles before placement of the pod on the interface port door. However, this technique requires additional manpower and fails to effectively clean particulate contaminants from the pod box door.
Accordingly, an object of the present invention is to provide an apparatus and method for preventing or reducing particle contamination of semiconductor integrated circuits or wafer substrates during the transport and processing of semiconductor wafers.
Another object of the present invention is to provide an apparatus and method for removing contaminants from a semiconductor wafer pod during transport and processing of semiconductor wafers in a semiconductor production facility.
Still another object of the present invention is to provide an apparatus and method for removing contaminants from the bottom surface of a semiconductor wafer pod using air or gas.
Yet another object of the present invention is to provide an apparatus which utilizes impingement of air in a sprinkling pattern against the surface of a semiconductor wafer pod to dislodge or remove particles from the pod in the transport and/or processing of semiconductor wafers.
A still further object of the present invention is to provide an apparatus and method which removes a substantial quantity of particulate contaminants from a semiconductor wafer pod to prevent or reduce the likelihood of particulate contamination of semiconductor integrated circuits or semiconductor wafer substrates in the production and/or transport of semiconductor wafers in a semiconductor production facility.
In accordance with these and other objects and advantages, the present invention comprises an apparatus including a rotatable air sprinkler which is mounted in a housing and connected to a source of clean, dry air (CDA). The air sprinkler rotates as the air is distributed under pressure through the sprinkler and ejected from nozzles in the sprinkler. The ejected air impinges against a semiconductor wafer pod placed on the housing, above the air sprinkler to dislodge or remove particulate contaminants from the pod and prevent or at least significantly reduce the likelihood of particle contamination during transport of the pod and/or processing of the wafers in the pod.